2-methacryloyloxyethyl Trimethyl Ammonium Chloride Research Articles

The preparation and performance test of a new type of water-absorbent resin dust suppressant with cation

In this paper, the cationic monomer was grafted into the dust suppressant molecule innovatively. The dust particles were adsorbed through net capture function, and the dust suppression efficiency was improved by charge interaction for dust particles’ electronegative. This experiment adopted the starch, acrylic acid and methacryloyloxyethyl trimethyl ammonium chloride (DMC) as raw materials, with potassium persulfate as initiator and glycerol as the crosslinking agent, synthesizing a new type of water-absorbent resin dust suppressant with cation (later called CNDS). After structure characterization and performance test, the results showed that the cationic monomer were successfully grafted and the CNDS had good functions of keeping moisture, wind-resistant, compressive resistance and anti-erosion. The viscosity of CNDS solution (2%) is 24.7 cP, which can bond and adsorb the dust particles in the air effectively. According to economic cost accounting, spraying CNDS only costs 0.46 yuan per square meter. Hence, there is a great prospect of promotion and application due to its low price.

Cationic kraft lignin-acrylamide copolymer as a flocculant for clay suspensions: (2) Charge density effect

Abstract Kraft lignin valorization is achievable via making it soluble in water for treating wastewater effluents. In this paper, acrylamide (AM), (2-methacryloyloxyethyl) trimethyl ammonium chloride (DMC) and kraft lignin (KL) were polymerized in an aqueous solution to produce a water-soluble lignin-based copolymer. Two cationic KAD polymers, with the same molecular weight, but different charge densities, were used as flocculants for simulated clay suspensions. The higher charge density copolymer (KAD1) had greater adsorption on kaolin (2.58 mg/g) and bentonite particles (1.83 mg/g) at 4 mg/g (based on clay) adsorption. Furthermore, KAD's higher charge density improved its performance in changing zeta potential and turbidity of the clay suspensions. At 4 mg/g copolymer dosage in clay suspensions, the particle size of kaolin was increased from 4.7 to 22.3 and 16.2 μm, and that of bentonite was increased from 6.1 to 31.9 and 19.8 μm for KAD1 and KAD2, respectively. In addition, the interfacial tension between water and kaolin and between water and bentonite dropped from 12.3 mN/m to 5.8 mN/m and from 9.5 mN/m to 5.2 mN/m when KAD1 was used, respectively. Moreover, KAD1 produced stronger flocs and showed high regrowth affinity at different shear rates.

Thermoresponsive Nanospheres with Entrapped Fluorescent Conjugated Polymers for Cellular Labeling.

Thermoresponsive fluorescent nanospheres were prepared by entrapping fluorescent conjugated polymers (FCP) into biocompatible copolymerized nanospheres comprised of methacryloyloxyethyltrimethylammonium chloride and n-isopropylacrylamide. A systematic study allowed monodisperse nanospheres ranging from 50 to 150 nm to be produced by precisely controlling the amount of monomer, initiator, and solvent during the dispersion polymerization process. The as-synthesized fluorescent nanospheres exhibited reversible temperature-dependent fluorescence with strong emission at lower temperature (20 °C) and weak emission at higher temperature (50 °C). Cell viability assays showed that the nanoshperes were nontoxic. The cellular imaging showed a rapid response in fluorescence intensity change upon variation of temperature in HeLa cells, indicating that our fluorescent probes are promising asin situ thermometers for labeling cells.

Synthesis of a novel tunable lignin-based star copolymer and its flocculation performance in the treatment of kaolin suspension

Abstract In current work, lignin-based multi-arm star copolymer phenolated kraft lignin-graft-poly (2-methacryloyloxyethyl) trimethyl ammonium chloride (PKL-g-PDMC) was designed and synthesized as a new kind of cationic flocculant via Steglich esterification of PKL and subsequent RAFT polymerization with DMC, and its flocculation performance in the removal of kaolin particles from simulated wastewater was evaluated. The star PKL-g-PDMCs with varying graft density and arm length of PDMCs chains were characterized by 1H NMR, 31P NMR, GPC and TGA. The effects of graft density and arm length, PKL-g-PDMC dosage, suspension pH and settling time on flocculating performance were investigated by measuring residual turbidity of the settled suspension. The treatment was effective, as demonstrated by 96.4% efficiency of turbidity removal. Above all, the chemical structure of the copolymers, including graft density and the arm length, can be designable and tunable by simply changing feeding ratios of Steglich esterification and subsequent RAFT polymerization, and thus the best flocculation performance can be obtained. This work provides a blueprint for the design, synthesis and use of novel lignin-based multi-arm star copolymers for wastewater treatment with tunable properties.

Cationic High Molecular Weight Lignin Polymer: A Flocculant for the Removal of Anionic Azo-Dyes from Simulated Wastewater.

The presence of dyes in wastewater effluents made from the textile industry is a major environmental problem due to their complex structure and poor biodegradability. In this study, a cationic lignin polymer was synthesized via the free radical polymerization of lignin with [2-(methacryloyloxy) ethyl] trimethyl ammonium chloride (METAC) and used to remove anionic azo-dyes (reactive black 5, RB5, and reactive orange 16, RO16) from simulated wastewater. The effects of pH, salt, and concentration of dyes, as well as the charge density and molecular weight of lignin-METAC polymer on dye removal were examined. Results demonstrated that lignin-METAC was an effective flocculant for the removal of dye via charge neutralization and bridging mechanisms. The dye removal efficiency of lignin-METAC polymer was independent of pH. The dosage of the lignin polymer required for reaching the maximum removal had a linear relationship with the dye concentration. The presence of inorganic salts including NaCl, NaNO3, and Na2SO4 had a marginal effect on the dye removal. Under the optimized conditions, greater than 98% of RB5 and 94% of RO16 were removed at lignin-METAC concentrations of 120 mg/L and 105 mg/L in the dye solutions, respectively.

Characterization and sludge dewatering performance evaluation of the photo-initiated cationic flocculant PDD

Abstract In this study, a novel flocculant called PDD was synthesized under ultraviolet irradiation using acrylamide (AM), methacryloyloxyethyl trimethylammonium chloride (DMC), and dimethyldiallylammonium chloride (DMDAAC) as monomers. The effects of monomer concentration, cationic degree, cationic monomer ratio, photo-initiation time, photo-initiator concentration, and pH value on the conversion rate and relative molecular mass of PDD were investigated through single-factor and orthogonal experiments. The microstructure of the synthesized product PDD was characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetry–differential thermal analysis, and proton nuclear magnetic resonance. The factors that ensure the optimal sludge dewatering performance of PDD obtained under the optimal synthesis conditions were as follows: flocculant dosage = 80 mg/L, pH value = 3, cationic degree = 60%, and relative molecular mass = 9.0 × 106. The solid content of the sludge filter cake, the residual turbidity of the filtrate, and the sludge specific resistance under the optimal synthesis conditions were 31.44%, 11.80 NTU, and 2.11 × 109 m/kg, respectively. Dewatering experimental results showed that PDD had significantly better sludge dewatering efficiency than the commercial flocculants. The main mechanisms for sludge conditioning were adsorption–bridging interaction and electrical neutralization after determining the zeta potential.

Improved antifouling properties of membranes by simple introduction of zwitterionic copolymers via electrostatic adsorption

In this study, a simple approach was proposed to incorporate zwitterionic copolymers into polymer membranes via electrostatic adsorption to reduce organic fouling and biofouling. Zwitterionic copolymers carrying positive charges were successfully synthesized from [2-(methacryloyloxy) ethyl] dimethyl-(3-sulfopropyl) ammonium hydroxide (SBMA) and [2-(methacryloyloxy) ethyl] trimethylammonium chloride (MTAC) via radical polymerization. Quartz crystal microbalance (QCM) measurements were conducted to identify the optimum copolymer with suitable monomer ratio for surface coating. The copolymer with an SBMA to MTAC ratio of 7:3, and 1000 ppm polymer concentration showed the highest adsorption. A negatively charged membrane was modified with this zwitterionic copolymer by the dip-coating method, which was finished in 1 min. The surface properties and antifouling properties (i.e. anti-organic fouling and anti-biofouling) of the membranes were characterized. Moreover, the modified membrane was stable in various chemical solutions. Results indicated that improved anti-organic fouling and anti-biofouling properties was attributed to improved hydrophilicity and reduced negative charge. The zwitterionic coating layer was stable after treatment with various solutions (e.g., 70% ethanol, 0.01 M sodium dodecyl sulfate (SDS), 0.1 M sodium chloride (NaCl), and a pH11 aqueous solution) for 6 h. This study provides a simple, stable method of modifying negatively charged membrane to improve antifouling properties, which is of great importance in biomedicine.

Optimizing the preparation conditions of amphoteric polyacrylamide as a strength additive for recycled paper

Abstract Acrylamide, itaconic acid and methacryloyloxyethyl trimethylammonium chloride were used to synthesize a series of amphoteric polyacrylamides (AmPAM) by aqueous solution polymerization through varying the pH, the reaction time, the temperature and the composition. The polymers were characterized by molecular weight and added in a recycled pulp furnish to make sheets. Paper strength was highest with the polymer made at pH 7 and 70 °C for 6 h with a monomer ratio of 2:0.3:0.3 (AM:IA:DMC) with 0.6 % initiator (based on the total mass of monomers). The optimized polymer was characterized by thermal gravity analysis, Fourier transform infrared spectroscopy and was then added at various pH and dosage level to the pulp alone or in combination with PAC, to determine the optimum addition conditions. Strength increased significantly with AmPAM addition level and PAC dosage but pH had little effect. The treated fibers were characterized by Zeta potential and drainage measurements. SEM showed the presence of a polymer film that is believed to reinforce inter-fiber bonds in the paper.

Hybrid Hydrogels Toughened by Chemical Covalent Bonding and Physical Electrostatic Interactions

Polystyrene nanoparticles with negative charges(n-PSs) were synthesized using styrene(St) and sodium styrene sulfonate(NaSS) as initial materials by surfactant-free emulsion polymerization. Subsequently, a hybrid hydrogel was prepared using acrylamide(AAm) and methacryloyloxyethyltrimethyl ammonium chloride(DMC) as co-monomers with N,N′-methylenebisacrylamide(MBA) as a chemical crosslinker and n-PSs as a physical electro- static interaction agent. The resulting hybrid hydrogels exhibited excellent tensile strength and elongation at break. The tensile stress of hybrid hydrogels was seven times greater than that of hydrogels without n-PSs. The elongation at break of hydrogels reached 700%, which was much higher compared to those of the hydrogels without n-PSs. Furthermore, swelling measurements of the hydrogels indicate that there is an overshoot in the swelling process and the extent of overshoot decreases with the increasing n-PSs. Therefore, the work presented here provides a method for improving the mechanical properties of hydrogels via the introduction of polymeric nanoparticles.

Novel Process for Generating Cationic Lignin Based Flocculant

Kraft lignin is currently under-utilized since it is primarily used as fuel in pulping processes. However, it can be used as a raw material to prepare a functional polymer such as flocculant. A cationic lignin polymer was synthesized via graft polymerization of lignin and [2- (methacryloyloxy)ethyl] trimethylammonium chloride (METAC) in an acidic environment (i.e., a heterogeneous system). The reaction, which was optimized under the conditions of pH 4.0, METAC/lignin ratio of 1.8 mol/mol, 3 h, 80 °C, 0.3 mol/L of lignin concentration, and 1.5 wt % of initiator dosage, generated a lignin-graft-PMETAC polymer having 2.93 mequiv/g charge density and 1.53 × 106 g/mol molecular weight. The lignin-graft-PMETAC polymer can be dissolved in water (at 10 g/L concentration) and a pH range of 0.5–13. The flocculation performance of the polymer was evaluated in a 0.25 wt % kaolin suspension using a particle dispersion analyzer, and the results demonstrated the superiority of the lignin-graft-PMETAC polymer to unmodifi...

Pectin graft copolymer-montmorillonite composite: Synthesis, swelling and divalent metal ion adsorption

ABSTRACTA novel graft copolymer gel made up of pectin (Pec), 2-(methacryloyloxyethyl)trimethylammonium chloride (METAC), 2-acrylamido-2-methyl-1-propane sulfonic acid (AMPS) and its composite with montmorillonite (MMT) were prepared using methylenebisacrylamide (MBA) as cross-linker via microwave irradiation and characterized using Fourier transform infrared (FTIR), Thermogravimetric Analysis (TGA) and Scanning electron microscopy (SEM) techniques. Swelling studies were carried out under different pH conditions. The graft copolymer gel and its composite showed maximum swelling in neural medium (pH 7.1) and the swelling process followed second order kinetics. The mechanism of water transport is found to be a Less Fickian diffusion process. The adsorption capacities of the graft copolymer gel and the composite towards divalent metal ions (Cu2+, Pb2+ and Hg2+) were evaluated. The adsorption capacity of the representative samples, Pec-g-poly(METAC-co-AMPS)-A5 and Pec-g-poly(METAC-co-AMPS)/MMT-C2 respectively for Cu2+ are 30.71 and 39.18 mg/g; for Pb2+ are 58.06 and 79.78 mg/g and for Hg2+ are 12.16 and 19.58 mg/g. The re-usability of the materials was also evaluated. The % recovery for the above two systems towards metals ion are 87.91 and 63.46 for Cu2+, 32.13 and 58.30 for Pb2+ and 78.53 and 51.92 for Hg2+. respectively. The adsorption isotherm studies indicated the adsorption of Pb2+, Cu2+ and Hg2+ in both samples is explained best by the Freundlich model except of Hg2+ by Pec-g-poly(METAC-co-AMPS)-A5, which is best explained by the Langmuir model.

Cationic xylan- (2-methacryloyloxyethyl trimethyl ammonium chloride) polymer as a flocculant for pulping wastewater

In this work, pulp mill wastewater was treated with a novel polymer flocculant, which was synthesized through polymerizing (2-methacryloyloxyethyl) trimethyl ammonium chloride (DMC) and xylan. Xylan-DMC polymer removed 94.5% of turbidity, 61.7% of chemical oxygen demand (COD), 45.0% of lignin, 65.7% of sugar and 73.5% of biological oxygen demand (BOD) from the wastewater at the polymer concentration of 500 mg/L. The flocculation mechanism was fundamentally assessed with determining hydrodynamic size and chord length of flocs in the wastewater at different dosages of xylan-DMC polymer in the system. By adding polymers, the number of flocs with a small chord length (10–50 μm) decreased, while that with a large chord length (150–300 μm) increased, indicating the small particles agglomerated via bridging induced by the polymer. The sedimentation of formed flocs was quantitatively investigated by a vertical scan analyzer and the results depicted that the flocs could settle readily from the system.

Surface and anti-fouling properties of a polyampholyte hydrogel grafted onto a polyethersulfone membrane

Zwitterion polymers have anti-fouling properties; therefore, grafting new zwitterions to surfaces, particularly as hydrogels, is one of the leading research directions for preventing fouling. Specifically, polyampholytes, polymers of random mixed charged subunits with a net-electric charge, offer a synthetically easy alternative for studying new zwitterions with a broad spectrum of charged moieties.Here, a novel polyampholyte hydrogel was grafted onto the surface of polyethersulfone membrane by copolymerizing a mixture of vinylsulfonic acid (VSA) and [2-(methacryloyloxy)ethyl]trimethylammonium chloride (METMAC) as the negatively and positively charged monomers, respectively, using various monomer ratios in the polymerization solution, and with N,N′-methylenebisacrylamide as the crosslinker. The physicochemical, morphological and anti-fouling properties of the modified membranes were systematically investigated.Hydrophilic hydrogels were successfully grafted using monomers at different molar ratios. A thin-film zwitterion hydrogel (∼90 nm) was achieved at a 3:1 [VSA:METMAC] molar ratio in the polymerization solution. Among all examined membranes, the zwitterion polyampholyte-modified membrane demonstrated the lowest adsorption of proteins, humic acid, and sodium alginate. It also had low fouling and high flux recovery following filtration with a protein or with an extracellular polymeric substance solution. These findings suggest that this polyampholyte hydrogel is applicable as a low fouling surface coating.

Surface molecular imprinting on carbon microspheres for fast and selective adsorption of perfluorooctane sulfonate

Perfluorooctane sulfonate (PFOS) is a persistent organic pollutant with high biological and chemical stability. It is important to develop fast and selective adsorption method for PFOS wastewater treatment. In this study, novel molecularly imprinted polymer (MIP) for PFOS adsorption was prepared. To obtain rapid adsorption kinetics, the MIP has been designed as the surface polymer using the carbon microsphere as carrier (MIP-CMSs). To ensure high adsorption selectivity to the template, two monomers with different functional structures, namely methacryloyloxyethyl trimethyl ammonium chloride (DMC) and 2-(trifluoromethyl)acrylic acid (TFMA), were employed as bi-functional monomers. The structure and morphology of MIP-CMSs were characterized using field emission scanning electron microscopy with the energy dispersive spectrometer, transmission electron microscopy, and Fourier transformation infrared spectroscopy. Based on the adsorption experiments, it was concluded that MIP-CMSs had specific binding property for PFOS on acidic condition. The adsorption equilibrium time was 1h, while the adsorption capacity was 75.99 mg g−1 at pH 3. Coexistence with contaminants with different structures had little influence on the selectivity for PFOS. The spent MIP-CMSs could be regenerated by the methanol and acetic acid mixed solution. The electrostatic interaction and molecular size played important roles in recognizing the target compound in the adsorption process.

In situ construction of dual-noncovalent bonding to prepare enhanced carbon nanotubes/poly(methyl methacrylate) nanocomposites

Interfacial interaction between carbon nanotubes (CNTs) and polymer matrix is crucial in preparing high-performance CNTs/polymer composites. In this work, dual-noncovalent bonding was constructed via in situ polymerization to improve the interfacial interaction between CNTs and polymer. Two functional monomers, 2-(methacryloyloxy) ethyltrimethyl ammonium chloride (MTC) and styrene (St), were utilized to copolymerize with methyl methacrylate (MMA) via in situ polymerization, meanwhile, carboxylic CNTs was adsorbed through electrostatic interaction and π-π interaction during the polymerization process. 1H NMR and GPC measurements verified that the successful synthesis of copolymer and its adsorption onto the surface of CNTs, while the enhanced interfacial interactions were confirmed by FTIR and Raman. Compared with neat PMMA, the thermal decomposition temperature and tensile strength of the composites were improved by 40 °C and 55.2%, respectively.

Effect of surface charge on osteoblastic proliferation and differentiation on a poly(ethylene glycol)-diacrylate hydrogel

Two charge monomers, namely 2-(methacryloyloxy)ethyl-trimethylammonium chloride (MAETAC) and sodium methacrylate (SMA), were incorporated into poly(ethylene glycol)-diacrylate (PEGDA) hydrogels to investigate the effects of surface charge on the proliferation and differentiation of osteoblasts. The physicochemical properties of the polymers were characterized, and MC3T3-E1 cells were seeded on the hydrogels to evaluate the effect of charge polarity and density on osteoblastic proliferation and differentiation. FTIR results revealed that the two charged monomers were successfully incorporated into PEGDA. The zeta potential of the hydrogels became more positive or negative with increasing concentration of MAETAC or SMA. The zeta potential of the charged hydrogels remained constant after immersion in culture medium for different time points. Other physicochemical properties such as surface morphology, swelling ratio in PBS, contact angle, and elastic modulus were not significantly different among each group with different concentrations of charge monomers incorporated into PEGDA. The modification of hydrogels with charge monomers not only improved osteoblastic proliferation but also upregulated alkaline phosphatase activity and the expression of osteogenic marker genes and relative growth factors. These findings indicate that, in contrast to charge polarity, the charge density would be more important to improve osteoblast-like cells proliferation and differentiation on the poly(ethylene glycol)-diacrylate hydrogel. The hydrogel can be designed by controlling the incorporation of charge monomers. This study provides a model to study the effect of charge on cell behavior.

Cellulose Nanocrystals with Tethered Polymer Chains: Chemically Patchy versus Uniform Decoration

The site-specific surface modification of colloidal substrates, yielding "patchy" nanoparticles, is a rapidly expanding area of research as a result of the new complex structural hierarchies that are becoming accessible to chemists and materials scientists through colloidal self-assembly. The inherent directionality of cellulose chains, which feature a nonreducing and a reducing end, within individual cellulose nanocrystals (CNCs) renders them an interesting experimental platform for the synthesis of asymmetric nanorods with end-tethered polymer chains. Here, we present water-tolerant reaction pathways toward patchy and uniformly modified CNC hybrids based on atom transfer radical polymerization (ATRP) and initiators that were linked to the CNCs with carbodiimide-mediated coupling and Fischer esterification, respectively. Various monomers, including N-isopropylacrylamide (NIPAM), [2-(methacryloyloxy)ethyl]trimethylammonium chloride (METAC), and sodium 4-vinylbenzenesulfonate (4-SS), were polymerized from both types of initiator-modified CNCs, yielding chemically patchy and uniform CNC hybrids, via surface-initiated ATRP (SI-ATRP). Interestingly, the stereochemistry of tethered PNIPAM was affected by the precise location of ATRP initiating sites, as evidenced by 1H NMR and circular dichroism (CD) spectroscopy. This effect may be related to the inherent right-handed chirality of CNCs. CNC/PMETAC hybrids were labeled with gold nanoparticles (AuNPs) in order to visualize the precise location of polymer tethers via cryo-electron microscopy. In some instances, the AuNPs were indeed concentrated at the end groups of the patchy CNC hybrids.

Influence of pH and ionic strength on flocculation of clay suspensions with cationic xylan copolymer

In this work, the influence of pH and ionic strength on the flocculation performance of cationic xylan copolymer in kaolin and bentonite suspensions was systematically investigated. The cationic xylan was produced via copolymerizing xylan with 2-(methacryloyloxy ethyl) trimethylammonium chloride (METAC), and the cationic xylan copolymer (CMX) showed a maximum adsorption of 4.6 and 1.8mg/g on kaolin and bentonite particles at the CMX dosage of 8mg/g, pH 10, 30°C and 1h, respectively. The reduction in charge density of CMX from 2.66 to 2.48meq/g was observed, with an increase in pH of CMX solution to from 2 to 10. The maximum increase in the zeta potential of kaolin (+54mV) and bentonite (−3mV) suspensions and the highest removal of kaolin (75%) and bentonite (96%) from the suspensions were obtained at 8mg/g CMX and pH 7. Stability studies revealed that pH had a noticeable influence on the sedimentation of kaolin and bentonite particles. CMX increased the destabilization index of kaolin (0.4–45) and bentonite (0.2–51) suspensions by increasing the floc size of kaolin and bentonite particles to 9.5μm and 12.7μm, respectively. CMX removed more of bentonite than kaolin at any pH under static and dynamic conditions. The impact of inorganic salts on the removal of kaolin particles was also studied. CMX exhibited better performance than a commercial flocculant (PDADMAC) in flocculating the commercially produced effluent.

Evaluation of the starch-based flocculants on flocculation of hairwork wastewater

China is the world's largest producer of wigs, and the manufacturing generates large quantities of hairwork effluents. Coagulation/flocculation is an important step in the water treatment process. In this study, two versions of starch-based flocculants were successfully prepared through etherification and graft copolymerization, respectively. Starch-3-chloro-2-hydroxypropyl triethyl ammonium chloride (St-CTA-DQ) and starch-graft-poly[(2-methacryloyloxyethyl) trimethyl ammonium chloride] (St-g-PDMC-DQ) both contain strongly cationic quaternary ammonium salt groups, but have differing cationic contents, specifically, the degree of substitution (DS) and grafting ratio (G). Furthermore, the additional functional groups were distributed on different chain sites (the starch backbone for St-CTA-DQ, and the branch chains for St-g-PDMC-DQ). These two flocculants demonstrated superior efficiency for turbidity and UV254 removal in hairwork wastewater as well as better floc properties compared to polyaluminum chloride. The effects of pH, flocculant dose, and cationic group contents (DS and G) were systematically investigated. Consequently, it was determined that a higher cationic content in both the flocculants led to better flocculation performance as well as increased removal rates of both turbidity and UV254. This was primarily due to improved charge neutralization, which highlighted the preference towards a lower optimal dose. In addition, flocculation performance worsened as the pH level increased. Overall, St-g-PDMC-DQ exhibited similar flocculation performance to St-CTA-DQ. However, the wastewater treated by St-g-PDMC-DQ showed lower residual turbidity than when treated by St-CTA-DQ. This was attributed to the distinct branch chain architecture of St-g-PDMC-DQ, which was beneficial for coagulating the uneasily flocculated contaminants in water, such as smaller-sized colloids and water-soluble organic substances. Flocculant structural factors, specifically charge properties and chain architecture, heavily affected the final flocculation performance.

Functionalized Carbon Nanotube and Graphene Oxide Embedded Electrically Conductive Hydrogel Synergistically Stimulates Nerve Cell Differentiation.

Nerve regeneration after injury is a critical medical issue. In previous work, we have developed an oligo(poly(ethylene glycol) fumarate) (OPF) hydrogel incorporated with positive charges as a promising nerve conduit. In this study, we introduced cross-linkable bonds to graphene oxide and carbon nanotube to obtain the functionalized graphene oxide acrylate (GOa) and carbon nanotube poly(ethylene glycol) acrylate (CNTpega). An electrically conductive hydrogel was then fabricated by covalently embedding GOa and CNTpega within OPF hydrogel through chemical cross-linking followed by in situ reduction of GOa in l-ascorbic acid solution. Positive charges were incorporated by 2-(methacryloyloxy)ethyltrimethylammonium chloride (MTAC) to obtain rGOaCNTpega-OPF-MTAC composite hydrogel with both surface charge and electrical conductivity. The distribution of CNTpega and GOa in the hydrogels was substantiated by transmission electron microscopy (TEM), and strengthened electrical conductivities were determined. Excellent biocompatibility was demonstrated for the carbon embedded composite hydrogels. Biological evaluation showed enhanced proliferation and spreading of PC12 cells on the conductive hydrogels. After induced differentiation using nerve growth factor (NGF), cells on the conductive hydrogels were effectively stimulated to have robust neurite development as observed by confocal microscope. A synergistic effect of electrical conductivity and positive charges on nerve cells was also observed in this study. Using a glass mold method, the composite hydrogel was successfully fabricated into conductive nerve conduits with surficial positive charges. These results suggest that rGOa-CNTpega-OPF-MTAC composite hydrogel holds great potential as conduits for neural tissue engineering.